Minimizing Waste from Existing Processes

The priorities for the work will be dependent on the objectives. For example, if the prime objective is to minimize total waste leaving the site then it may be preferable to select a process that has a large aqueous 

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Waste disposal. In recent years, many legal restrictions have been placed on the methods for disposing of waste materials from the process industries. The site selected for a plant should have adequate capacity and facilities for correct waste disposal. Even though a given area has minimal restrictions on pollution, it should not be assumed that this condition will continue to exist. In choosing a plant site, the permissible tolerance levels for various methods of waste disposal should be considered carefully, and attention should be given to potential requirements for additional waste-treatment facilities. 

Renewable raw materials can contribute to the sustainability of chemical products in two ways (i) by developing greener, biomass-derived products which replace existing oil-based products, e.g. a biodegradable plastic, and (ii) greener processes for the manufacture of existing chemicals from biomass instead of from fossil feedstocks. These conversion processes should, of course, be catalytic in order to maximize atom efficiencies and minimize waste (E factors) but they could be chemo- or biocatalytic, e.g. fermentation [3-5]. Even the chemocatalysts themselves can be derived from biomass, e.g. expanded com starches modified with surface S03H or amine moieties can be used as recyclable solid acid or base catalysts, respectively [6]. 

Opportunities exist to minimize waste through the planning and structure of industrial development, where surplus process or utility streams from one plant or industrial facility can usefully be utilized by separate plants or facilities. This exchange can often be across distinct industry sectors. 

Assurances that new and existing chemical processes are conducted safely have never been more needed. Public awareness of the effects of chemical exposure has increased since the early 1970s. Although the initial focus of the Occupational Safety and Health Act of 1970 was on safety, clearly the emphasis now is on health. People at all levels of society are concerned about exposure to chemicals and the possible short- and longterm effects of chemicals on human health. The effects of chemicals on the environment from past or present waste sites, accidental releases or spills, and fires and explosions are reported daily in the news media. Control of all chemical processes to avoid accidental discharges and/or upsets that lead to fires, explosions, and environmental release is essential in the laboratory, the pilot plant, and the manufacturing plant. Chemical process hazard reviews are necessary at each step in the development of a process to ensure that the process can be controlled and conducted so as to minimize the risks to personnel, property, and the environment. 

Direct contact condensers are inexpensive and the penalty for oversizing is minimal if cooling-water pumping costs are not prohibitive. They can be built from a variety of materials. The primary consideration in applying these condensers Is their environmental impact. If the cooling water will require waste treatment as a result of contact with process vapors, the waste treatment cost will usually be prohibitive and economics will dictate the use of surface condensers. Many existing direct contact condensers are being or have been replaced with surface condensers for this reason. 

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